Single DC Voltage Source Research Articles

A new bidirectional hybrid multilevel inverter with 49-level output voltage using a single dc voltage source and reduced number of on components

This paper proposes an isolated bidirectional asymmetrical multilevel inverter topology composed by an H-bridge (HB) inverter connected to the primary side of transformer. The transformer secondary side is composed by two windings, and each one is connected to a new cell introduced in this work. The proposed new cell is based on the conventional HB inverter, where two bidirectional switches are added to each HB leg, thus resulting in the structure referred to as CHB-2bs. The transformer can also be composed by multiple secondary winding in order to provide the necessary voltages to supply as many as CHB-2bs cells are. A 600W laboratory prototype with dc input voltage of 48V and an ac output voltage of 220V, 60Hz using a grain-oriented silicon–steel toroidal transformer operating at 300Hz is implemented to validate the theoretical assumptions and the advantages addressed to the CHB-2bs cell.

A Multilevel Converter With a Floating Bridge for Open-End Winding Motor Drive Applications

This paper presents a three-phase open-end winding induction motor drive. The drive consists of a three-phase induction machine with open stator phase windings and dual-bridge inverter supplied from a single dc voltage source. To achieve multilevel output voltage waveforms, a floating capacitor bank is used for the second of the dual bridges. The capacitor voltage is regulated using redundant switching states at half of the main dc-link voltage. This particular voltage ratio (2:1) is used to create a multilevel output voltage waveform with three levels. A modified modulation scheme is used to improve the waveform quality of this dual inverter. This paper also compares the losses in the dual-inverter system in contrast with a single-sided three-level neutral point clamped converter. Finally, detailed simulation and experimental results are presented for the motor drive operating as an open-loop v / f controlled motor drive and as a closed-loop field-oriented motor controller.

Reduced common‐mode voltage operation of a new seven‐level hybrid multilevel inverter topology with a single DC voltage source

In this study, analysis of extending the linear modulation range of a zero common-mode voltage (CMV) operated n-level inverter by allowing reduced CMV switching is presented. A new hybrid seven-level inverter topology with a single DC supply is also presented in this study and inverter operation for zero and reduced CMV is analysed. Each phase of the inverter is realised by cascading two three-level flying capacitor inverters with a half-bridge module in between. Proposed inverter topology is operated with zero CMV for modulation index <86% and is operated with a CMV magnitude of V-dc/18 to extend the modulation range up to 96%. Experimental results are presented for zero CMV operation and for reduced common voltage operation to extend the linear modulation range. A capacitor voltage balancing algorithm is designed utilising the pole voltage redundancies of the inverter, which works for every sampling instant to correct the capacitor voltage irrespective of load power factor and modulation index. The capacitor voltage balancing algorithm is tested for different modulation indices and for various transient conditions, to validate the proposed topology.

English

A single phase five level inverter with a dual reference single carrier Pulse Width Modulated (PWM) control scheme is presented. The inverter is capable of producing five levels of output voltage levels (Vdc, Vdc/2, 0, −Vdc/2, −Vdc) from the dc supply voltage. For this, the proposed multilevel inverter needs a single dc voltage source with a series connection of two capacitors, a bidirectional switch formed with four diodes and a switch, and an Hbridge cell. The proposed approach helps in reducing the number of independent dc voltage sources and number of switches as compared with conventional circuits.

7-level PWM Inverter Employing Series-Connected Capacitors Paralleled to a Single DC Voltage Source

This paper presents an effective circuit configuration of a multilevel inverter that can increase the number of output voltage levels with a reduced number of circuit components. The proposed seven-level pulsewidth-modulation inverter consists of a single dc voltage source with a series of capacitors, diodes, active switches for synthesizing output voltage levels, and an H-bridge cell. After theoretical analysis, we carry out computer-aided simulations and experiments to verify the validity of the proposed approach. Here, we also introduce a modified switching strategy to solve the capacitor voltage unbalancing that occurs in series-connected capacitors.

Unification of Buck-boost and Flyback Converter for Driving Cascaded H-bridge Multilevel Inverter with Single Independent DC Voltage Source

It presents a unification of buck-boost and flyback converter for driving a cascaded H-bridge multilevel inverter with a single independent DC voltage source. Cascaded H-bridge multilevel inverter is useful to make many output voltage levels for sinusoidal waveform by combining two or more H-bridge modules. However, each H-bridge module needs an independent DC voltage source to generate multi levels in an output voltage. This topological characteristic brings a demerit of increasing the number of independent DC voltage sources when it needs to increase the number of output voltage levels. To solve this problem, we propose a converter combining a buck-boost converter with a flyback converter. The proposed converter provides independent DC voltage sources at back-end two H-bridge modules. After analyzing theoretical operation of the circuit topology, the validity of the proposed approach is verified by computer-aided simulations using PSIM and experiments.

Cascaded H-bridge Multilevel Inverter employing Front-end Flyback Converter with Single Independent DC Voltage Source

Cascaded H-bridge multilevel inverter requires independent DC voltage sources to produce multi output voltage levels. When it needs to generate more levels in the output voltage wave, the number of independent DC voltage sources usually limits its extension. To solve this problem, we propose a cascaded H-bridge multilevel inverter employing a front-end flyback converter for unifying input DC voltage sources. After theoretical analysis of the proposed circuit, we verify the validity of the proposed inverter using computer-aided simulations and experiments.

Single switch dual output DC-DC converter performance

The performance of the single-switch dual-output DC-DC converter is evaluated. This converter regulates two independent DC outputs supplied from a single DC voltage source using a power semiconductor switch. Two discrete proportional feedback control loops regulate the duration of on switching and off switching. The duty cycle of the switch controls one output voltage, supplied from a low-pass filter, while the switching frequency regulates the other output voltage, supplied from a higher-frequency bandpass filter. The control algorithm is implemented with an Intel 8096 microcontroller. The experimental data demonstrate the actual circuit performance and confirm the simulation results. Both experiments and simulation show that an increase in the load current on the 12 V output results in an increase in the duty cycle, whereas an increase in the load current on the 5 V output results in a change in the switching frequency. The experimental prototype demonstrates operation over a load current range from about 40% to 100% with a +or-25% variation in the 24 V input. Full load currents are 12 A and 2.5 A on the 12 V and 5 V outputs, respectively. The switching frequency ranged from approximately 29 kHz to 264 kHz, and the duty cycle ranged from 0.35 to 0.72.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis and Modeling of a Single-Phase Brushless DC Motor Drive System

Brushless dc motors are becoming widely used in low-power applications such as blower motors, computer disk-drive spindle motors, and in copiers and laser printers. For these applications, the brushless dc motor offers the following advantages: small size, reliability, no carbon dust from brushes, precise speed control, and potentially high efficiency. The most commonly used brushless dc motors are twoor three-phase permanent-magnet ac machines driven by a dc-to-ac inverter. The three-phase machine combined with a six-pulse full-bridge inverter often represents the best trade-off of machine iron and copper utilization with the cost of the inverter. Because of the prevalence of two-and three-phase devices, they are the brushless dc motors which have been analyzed the most extensively. On the other hand, there has been little investigation into the operation of the single-phase brushless dc motor. Single-phase motors, in general, suffer from slower starting characteristics, less efficient utilization of machine iron and copper, and higher losses. Therefore, single-phase motors are limited to low-power applications where rapid response and high efficiency are not required. The primary advantage of single-phase devices is the simplified source requirements. For example, a single-phase brushless dc motor requires only one-third the number of transistors and position sensors needed by a three-phase motor and can be powered by a single dc voltage source. Thus, in applications where cost is of greater importance than performance, the single-phase motor may be a superior alternative to a two-or three-phase motor.